Soldato
That's how I ended up with my cat: he turned up a few times over the course of a summer, was very affectionate and would sit with us for a few hours before disappearing again. Then one very cold winter's night he came in and stayed. We took him to the vet, found he was chipped and contacted his owners - we'd wondered if he'd been abused or abandoned, until we met them and found they were devastated he'd left. He'd been well cared for, well loved and still had a brother living with them. We tried to send him home with them but as soon as they unlocked the cat flap he was off and back at ours. I guess sometimes they just fancy a change?
Probably his brother had a lot to do with it. Just because they get on OK doesn't mean they want to live together.